An alpheid shrimp digs and maintains a deep burrow. while underground, the shrimp is safe. above ground, it is vulnerable to predators. a goby fish lives in the burrow with the shrimp. the goby fish sits at the entrance, keeping watch for predators, and signals the shrimp with a flick of its tail when it is safe to come out. or, if a predator swims by, the goby darts into the burrow and the shrimp retreats further inside. these two animals are completely dependent on each other—the goby benefits by getting a burrow to live in and the shrimp knows when predators are near.

Your starship, the aimless wanderer, lands on the mysterious planet mongo. as chief scientist-engineer, you make the following measurements: a 2.50-kg stone thrown upward from the ground at 14.0 m/s returns to the ground in 5.70 s ; the circumference of mongo at the equator is 2.20×10^5 km ; and there is no appreciable atmosphere on mongo. (a) the starship commander, captain confusion, asks for the following information: what is the mass of mongo? (b) if the aimless wanderer goes into a circular orbit 2.20×10^4 km above the surface of mongo, how many hours will it take the ship to complete one orbit? (c) an unmanned spacecraft is in a circular orbit around the moon, observing the lunar surface from an altitude of 44.0 km . to the dismay of scientists on earth, an electrical fault causes an on-board thruster to fire, decreasing the speed of the spacecraft by 23.0 m/s . if nothing is done to correct its orbit, with what speed (in km/h) will the spacecraft crash into the lunar surface?